Artemether and artesunic acid, two synthetic Chinese antimalarials derived from the Chinese drug qinghaosu from Artemisia were characterized and their configuration established. Dihydroqinghaosu and its epoxy analog, both metabolites of qinghaous in man, were converted into DADF-ester derivatives, analyzed on tlc-plates after exposure to ammonia and iodine as red colored erythrosyl derivatives. This is a highly sensitive assay allowing detection of 0.1 - 1 Lambda of material.